Question

A bag contains 4 white balls and some red balls. If the probability of drawing a white ball from the bag is 2/5, find the number of red balls in the bag.

Answer 1

Let the no pf red ball be x so
2/5=4/x+4
8+4x=20
2x=20-8=12
x=12/2=6
No of red ball is 6

Answer 2

Answer:

6

Step-by-step explanation:

Let the no. of red balls be x

white balls = 4

Total balls = 4+x

Probability of getting white ball $=\frac{\text{no. of white balls}}{\text{Total no. of balls}}$

                                                    $=\frac{4}{4+x}$

We are given that  the probability of drawing a white ball from the bag is 2/5

So, $\frac{2}{5}=\frac{4}{4+x}$

$8+2x=20$

$2x=12$

$x=6$

Hence the number of red balls in the bag is 6